This invention relates to output over-voltage reduction in switching regulators. Methods and circuits are provided for reducing voltage overshoot at the output of switching voltage regulators operating in burst mode.
Switching regulators are used to provide stable voltage and current supplies. Switching regulators may be used to produce DC voltages of various amplitudes from DC input voltages of smaller or greater amplitude than the output voltage. Switching regulators may also be used to produce DC voltages of various amplitudes from AC input voltages.
Switching regulator circuits consume power even when the regulator is supplying little or no power to a load. In order to reduce the power consumption of switching regulators when they are providing little or no power to their load, switching regulators may be configured to operate in a power saving mode, or Burst Mode™. When operating in the Burst Mode, a switching regulator may monitor the power being consumed at its output and may alternate between two states of operation, a SLEEP state and a WAKE state, depending on the output load power requirements. If the load requires little or no power, the regulator may go into the SLEEP state in which the regulator switching circuits are substantially turned OFF in order to conserve power. If the load requires more power, the regulator may go into the WAKE state in which the switching circuits are turned ON and supply power to the output load.
While switching regulators may include Burst Mode control circuitry operative to put the regulator in either the WAKE or SLEEP state depending on the load power requirements, the circuitry may detrimentally affect the performance of the regulator. For example, the circuitry may limit the regulator's ability to maintain a stable regulator output voltage or current by allowing the output signal to vary excessively. The circuitry may also cause the regulator to remain in the WAKE state even though the load no longer requires large amounts of power.